The proposed studies represent the continuation of an ongoing investigation of thermoregulation in the neonatal mammal. With the use of puppy models, the metabolic and core temperature responses to cold stress will be determined and the role of adrenergic receptors in controlling these responses will be examined. The effects of acute and chronic hypoxia (singly and in combination) on these cold responses are to be studied. In addition, we will evaluate the efficacy of glucose and insulin infusions as a method of preventing the development of hypothermia caused by acute hypoxia. Acute hypoxia will be induced by ventilating animals with low oxygen mixtures and chronic hypoxia will be produced with a surgically-created right-to-left shunt. It is hoped that the information gained from the proposed investigation will increase our understanding of the physiology of thermoregulation and will help to improve the management of infants hypoxic from cardiopulmonary disease.